Multiple herbicide strategy has become the foundation for weed control programs

As weed control in the Mid-South evolves from a single technology to one with multiple modes of action, older farmers are learning new tricks and younger ones are finding out about older products. That’s especially true on the farm of Marty White, who farms with his sons, Jesse Flye and Logan White, growing cotton, soybeans, rice, corn and wheat near Jonesboro, Ark.

Weed control technologies include Genuity Roundup Ready 2 Yield and LibertyLink soybeans and cotton, and Clearfield rice. Conventional rice is also produced on the farm.

On the White/Flye farm, about 60 percent of the cotton is LibertyLink and 40 percent Genuity Roundup Ready 2 Yield. All double-cropped soybeans were LibertyLink technology this year because White and Flye had doubts about whether they could apply their residual herbicides in a timely manner.

They also planted LibertyLink soybeans in fields with a history of resistant weeds. These are usually newly-acquired fields, but this season included fields where floodwaters from 2011 brought in weed seed.

The farm acquired about 2,500 additional acres of cropland this year, and both White and Flye knew there would be problem fields. “We also had some fields on the south end of the farm where the floods hurt us last year by spreading pigweed seed,” White says. “We put those in LibertyLink, too. On our non-infested fields, we used Genuity Roundup Ready 2 Yield.”

While using multiple modes of action is crucial for managing resistance, everyone knows there is less margin for error than in pre-resistance days, no matter what the technology.

“If we don’t get our residuals activated behind our soybeans, we are in for a long row to hoe,” White says. “We apply Valor on LibertyLink and Genuity Roundup Ready 2 Yield fields. Both technologies are treated the same, except for the post product.”

In a multiple technology operation, “You have to put the technology in the right fields,” Flye says. “On problem fields, we can clean up with Liberty,” White says. “But Liberty is better on broadleaves, and Roundup is better on grasses. Liberty limits you as to when you can spray — you can’t apply Liberty on soybeans after the first bloom. With Roundup you have a little more flexibility.”

The farm’s work crew is also dealing with more complexity these days, much of which is aimed at avoiding a spraying misstep. Color-coded maps are in all sprayers to help drivers determine where the different technologies are being used. They also use the flag system on all of their fields.

“A lot of times, we may have three crops adjoining each other,” Flye says. “We’ve learned to be careful when we’re spraying. We have two new high clearance sprayers. Both herbicides clean out very easily.”

White points out, “You’re only as good as your labor, and we have good labor; I’d put them up against anybody around.”

One thing that should help sort out the differences between LibertyLink and Genuity Roundup Ready 2 Yieldtechnologies are large, side-by-side trials planted on the farm this season.

White and Flye are working with Asgrow territorial agronomist Bradley Jackson on the trials, which will break down total costs, including residual herbicides and supplemental chopping.

White and Flye both say the Genuity Roundup Ready 2 Yield technology may end up being a little cheaper in terms of weed control. The farm will chop both
Genuity Roundup Ready 2 Yield and LibertyLink soybeans, but may do more chopping in Genuity Roundup Ready 2 Yield.

For both LibertyLink and Genuity Roundup Ready 2 Yield soybeans, they will burn down with Gramoxone prior to planting. “Right before or right after the planter, we apply
Valor, then 10 days to 14 days later, we come back with Prefix,” White says. “This year, we got a rain right after that. We were lucky. We had good weed control with both technologies.”

If residuals in Genuity Roundup Ready 2 Yield soybeans don’t receive an activating rain, they will come back with Flexstar, which will kill smaller pigweed.

“Our fields usually don’t get so bad that a chopping crew can’t come in and take care of it,” White says. “When you start talking about $15 an acre for chopping, Flexstar is expensive. On a lot of fields with light pressure, we can get across the field with choppers for $5 an acre. Liberty and Prefix is a $25 application, while Prefix and Roundup is $18 to $20 per acre.”

The farm also deals with glyphosate-resistant horseweed, but that’s not much of a problem anymore, White says.

When resistant weeds are an issue in a field, the technology chosen can be a compromise between yield and weed control. They tried the LibertyLink technology last year in cotton test plots.

“It was really clean where we could get our residuals out,” White says. “Those varieties yielded comparably with our other varieties. They might have been off just a little bit, but a lot of times you don’t have a choice — you may be so grown up that you’re going to lose yield because of weed competition or because of variety selection.

“The fields where we planted LibertyLink cotton varieties, we can afford to give up 100 pounds of yield to keep them clean. In soybeans, you can give up some yield for weed control too. But I wouldn’t want to give up more than 5 bushels per acre, especially at today’s soybean prices.”

They planted twin-row soybeans for both their Genuity Roundup Ready 2 Yield and LibertyLink systems this year. White says twin row “canopies a lot quicker than a single row system and can help us rob developing pigweed of sunlight.”

Dealing with multiple technologies has been a learning experience for both Flye and White.

As a young boy, Flye recalls his father applying Prowl on fields prior to the advent of Genuity Roundup Ready 2 Yield technology, but today Flye is essentially learning about residuals for the first time. White remembers residuals all too well, but is learning how new technologies fit with the Genuity Roundup Ready 2 Yield.

These days, almost every farmer has a hoe in the back of his pickup truck, and White and Flye have picked up the habit, too.

“Zero tolerance is a term that is heard quite often,” says White, referring to a University of Arkansas approach that attempts to prevent any pigweed plant from going to seed.

“It doesn’t mean that pigweed will eventually be eradicated with this concept. But it has increased awareness of the dangers that even a single pigweed in a field can cause.

“We’ve never stopped chopping our cotton,” White says. “I think that’s one reason we aren’t run over with pigweed. When the flood came in 2011, that changed it for us — that’s why we used more LibertyLink this year.”

Both LibertyLink and Genuity Roundup Ready 2 Yield have weaknesses, they note, so it’s crucial that they make the right management decisions about where to use them.

But one thing is certain: “There are always going to be residuals,” Flye says. “Even the new technologies aren’t going to do what Genuity Roundup Ready 2 Yield did.”